Nozzle exit contours for pattern composition

ABSTRACT

A deposition nozzle is provided that includes offset deposition apertures disposed between exhaust apertures on either side of the deposition apertures. The provided nozzle arrangements allow for deposition of material with a deposition profile suitable for use in devices such as OLEDs.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional of, and claims the prioritybenefit of U.S. Patent Application Ser. Nos. 62/320,981, filed Apr. 11,2016, and 62/409,404, filed Oct. 18, 2016, the entire contents of eachof which is incorporated herein by reference.

PARTIES TO A JOINT RESEARCH AGREEMENT

The claimed invention was made by, on behalf of, and/or in connectionwith one or more of the following parties to a joint universitycorporation research agreement: Regents of the University of Michigan,Princeton University, University of Southern California, and theUniversal Display Corporation. The agreement was in effect on and beforethe date the claimed invention was made, and the claimed invention wasmade as a result of activities undertaken within the scope of theagreement.

FIELD OF THE INVENTION

The present invention relates to arrangements for depositing materialsuch as via one or more nozzles, and devices such as organic lightemitting diodes and other devices, including the same.

BACKGROUND

Opto-electronic devices that make use of organic materials are becomingincreasingly desirable for a number of reasons. Many of the materialsused to make such devices are relatively inexpensive, so organicopto-electronic devices have the potential for cost advantages overinorganic devices. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on a flexible substrate.Examples of organic opto-electronic devices include organic lightemitting devices (OLEDs), organic phototransistors, organic photovoltaiccells, and organic photodetectors. For OLEDs, the organic materials mayhave performance advantages over conventional materials. For example,the wavelength at which an organic emissive layer emits light maygenerally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage isapplied across the device. OLEDs are becoming an increasinglyinteresting technology for use in applications such as flat paneldisplays, illumination, and backlighting. Several OLED materials andconfigurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full colordisplay. Industry standards for such a display call for pixels adaptedto emit particular colors, referred to as “saturated” colors. Inparticular, these standards call for saturated red, green, and bluepixels. Color may be measured using CIE coordinates, which are wellknown to the art.

One example of a green emissive molecule is tris(2-phenylpyridine)iridium, denoted Ir(ppy)₃, which has the following structure:

In this, and later figures herein, we depict the dative bond fromnitrogen to metal (here, Ir) as a straight line.

As used herein, the term “organic” includes polymeric materials as wellas small molecule organic materials that may be used to fabricateorganic opto-electronic devices. “Small molecule” refers to any organicmaterial that is not a polymer, and “small molecules” may actually bequite large. Small molecules may include repeat units in somecircumstances. For example, using a long chain alkyl group as asubstituent does not remove a molecule from the “small molecule” class.Small molecules may also be incorporated into polymers, for example as apendent group on a polymer backbone or as a part of the backbone. Smallmolecules may also serve as the core moiety of a dendrimer, whichconsists of a series of chemical shells built on the core moiety. Thecore moiety of a dendrimer may be a fluorescent or phosphorescent smallmolecule emitter. A dendrimer may be a “small molecule,” and it isbelieved that all dendrimers currently used in the field of OLEDs aresmall molecules.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” a second layer, the first layer is disposedfurther away from substrate. There may be other layers between the firstand second layer, unless it is specified that the first layer is “incontact with” the second layer. For example, a cathode may be describedas “disposed over” an anode, even though there are various organiclayers in between.

As used herein, “solution processible” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed thatthe ligand directly contributes to the photoactive properties of anemissive material. A ligand may be referred to as “ancillary” when it isbelieved that the ligand does not contribute to the photoactiveproperties of an emissive material, although an ancillary ligand mayalter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled inthe art, a first “Highest Occupied Molecular Orbital” (HOMO) or “LowestUnoccupied Molecular Orbital” (LUMO) energy level is “greater than” or“higher than” a second HOMO or LUMO energy level if the first energylevel is closer to the vacuum energy level. Since ionization potentials(IP) are measured as a negative energy relative to a vacuum level, ahigher HOMO energy level corresponds to an IP having a smaller absolutevalue (an IP that is less negative). Similarly, a higher LUMO energylevel corresponds to an electron affinity (EA) having a smaller absolutevalue (an EA that is less negative). On a conventional energy leveldiagram, with the vacuum level at the top, the LUMO energy level of amaterial is higher than the HOMO energy level of the same material. A“higher” HOMO or LUMO energy level appears closer to the top of such adiagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled inthe art, a first work function is “greater than” or “higher than” asecond work function if the first work function has a higher absolutevalue. Because work functions are generally measured as negative numbersrelative to vacuum level, this means that a “higher” work function ismore negative. On a conventional energy level diagram, with the vacuumlevel at the top, a “higher” work function is illustrated as furtheraway from the vacuum level in the downward direction. Thus, thedefinitions of HOMO and LUMO energy levels follow a different conventionthan work functions.

More details on OLEDs, and the definitions described above, can be foundin U.S. Pat. No. 7,279,704, which is incorporated herein by reference inits entirety.

As used herein, “a direction of relative movement” or, more generally,“parallel” to a direction, refers to a direction approximately parallelto a direction of relative movement of a substrate and a depositionapparatus when the apparatus is used to deposit material on thesubstrate while the substrate and apparatus are moved relative to oneanother, within the tolerance required by the material being depositedor a device being fabricated. Thus, an aperture or other feature of adeposition device may be described as being arranged in or parallel to adirection of relative movement when the major axis, longest edge, etc.of the feature is parallel to the direction of relative movement withinthe required tolerance, even though the two may not be exactly parallel.For example, when depositing a stripe of emissive material for use in anOLED, it may be required that there be no more than 5 μm deviation inthe stripe placement or deposition accuracy over the surface of thesubstrate, in which case a deposition aperture may be arranged parallelto the relative direction of movement with sufficient accuracy toachieve the required deviation or less, i.e., parallel to the directionof relative movement. Similarly, a feature may be parallel orperpendicular to a direction or other feature when it is as close toperfectly parallel or perpendicular as fabrication tolerances allow,and/or within any required design or fabrication tolerance for thesystem.

SUMMARY OF THE INVENTION

According to an embodiment, a device for deposition of a material onto asubstrate, such as a print head or a deposition that includes a printhead is provided, which includes a deposition nozzle having a firstexhaust aperture, a second exhaust aperture, a first deposition aperturedisposed between the first exhaust aperture and the second exhaustaperture and closer to the first exhaust aperture than the secondaperture, and a second deposition aperture disposed between the firstexhaust aperture and the second exhaust aperture and closer to thesecond exhaust aperture than the first exhaust aperture, wherein thesecond deposition aperture is offset from the first deposition aperturealong an axis of the nozzle.

The first deposition aperture and the second deposition aperture mayhave the same dimensions, and each may be arranged such that a longestedge of each deposition aperture is along a direction of relativemovement of the device and the substrate when the device is inoperation. The apertures may be rectangular or any other suitable shape.The exhaust apertures may be continuous and/or rectangular, and may bearranged such that the longest edge of each is along a direction ofrelative movement of the device and the substrate when the device is inoperation. The apertures may be arranged in various relative positions.For example, they may be arranged such that for any line drawn betweenand perpendicular to the first exhaust aperture and the second exhaustaperture, the line crosses no more than one of the first depositionaperture or the second deposition aperture. Alternatively or inaddition, the exhaust apertures may extend ahead of and behind each ofthe first deposition aperture and the second deposition aperture in thedirection of relative movement of the device and the substrate when thedevice is in operation. The may include a source of the material to bedeposited on the substrate, in fluid communication with the firstdeposition aperture and the second deposition aperture. The device mayinclude an external vacuum source in fluid communication with one ormore of the exhaust apertures. The device may include source ofconfinement gas in fluid communication with one or more of the exhaustapertures. The exhaust apertures may each have a constant width along adirection of relative motion of the substrate and the device.

In an embodiment, a device is provided that includes an OLED. The OLEDmay include a first electrode disposed over a substrate, a firstemissive layer disposed over the first electrode, and a second electrodedisposed over the emissive layer. The first emissive layer may befabricated using no more than one pass of a deposition device comprisinga nozzle in fluid communication with a source of material to bedeposited over the substrate in not more than 1.0 s between theinitiation and conclusion of deposition on each point on the printedsurface of the substrate. The device may be, for example, a flat paneldisplay, a computer monitor, a medical monitor, a television, abillboard, a light for interior or exterior illumination and/orsignaling, a heads-up display, a fully or partially transparent display,a flexible display, a laser printer, a telephone, a cell phone, atablet, a phablet, a personal digital assistant (PDA), a laptopcomputer, a digital camera, a camcorder, a viewfinder, a micro-display,a virtual reality display, an augmented reality display, a 3-D display,a vehicle, a large area wall, a theater or stadium screen, a sign, or acombination thereof.

In an embodiment, a method of fabricating a deposition device isprovided that includes dicing a wafer pair to form micronozzle arraychannels comprising a plurality of deposition apertures along the edgesof each wafer, each aperture being defined by the intersection of achannel and a dicing line; and bonding the wafer pair to form adeposition nozzle. The deposition nozzle may include a first exhaustaperture, a second exhaust aperture, a first deposition aperturedisposed between the first exhaust aperture and the second exhaustaperture and closer to the first exhaust aperture than the secondaperture, and a second deposition aperture disposed between the firstexhaust aperture and the second exhaust aperture and closer to thesecond exhaust aperture than the first exhaust aperture, where thesecond deposition aperture is offset from the first deposition aperturealong an axis of the nozzle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light emitting device such as may be fabricatedaccording to techniques and devices disclosed herein.

FIG. 2 shows an inverted organic light emitting device that does nothave a separate electron transport layer such as may be fabricatedaccording to techniques and devices disclosed herein.

FIG. 3 shows a general deposition profile achievable according toembodiments disclosed herein.

FIG. 4 shows examples of deposition profiles and associated distributiontypes as disclosed herein.

FIG. 5 shows an example of a deposition pattern having a central widthwith high uniformity according to an embodiment disclosed herein.

FIG. 6 shows an example of a deposition profile formed from threedepositions.

FIG. 7 shows example nozzle aperture arrangements according toembodiments disclosed herein.

FIGS. 8A, 8B, and 8C show example nozzle aperture arrangements accordingto embodiments disclosed herein.

FIGS. 9 and 10 show example deposition profiles resulting from differentsections of the nozzle aperture arrangements disclosed herein.

FIGS. 11A, 11B, and 11C, respectively, show the partial contributions inthe x-direction at different y-sections of depositions resulting fromarrangements as shown in FIGS. 8A, 8B, and 8C.

FIGS. 12A, 12B, and 12C show, respectively, the weighted sum of theprofiles of depositions resulting from arrangements as shown in FIGS.8A, 8B, and 8C.

FIG. 13 shows an example depositor used in an OVJP process and amicronozzle array according to an embodiment disclosed herein.

FIG. 14 shows streamlines of a process gas flow generated by a depositoras shown in FIG. 13 according to an embodiment disclosed herein.

FIG. 15A shows a cross-sectional profile of the thickness of a thin filmfeature printed by a depositor with a single delivery aperture in onepass according to an embodiment disclosed herein.

FIG. 15B shows a cross-sectional profile of the thickness of a thin filmfeature printed by a depositor with a single delivery aperture in twopasses according to an embodiment disclosed herein.

FIG. 16A shows a depositor with a split and offset delivery aperture andthe thickness profiles of features printed by the upper half of thedepositor for various exhaust flow rates and aperture offsets accordingto an embodiment disclosed herein.

FIG. 16B shows deposition profiles resulting from asymmetry of DEspacers according to an embodiment disclosed herein.

FIG. 17A and FIG. 17B show cross-sectional thickness profiles offeatures printed by a depositor with a split delivery aperture forexhaust flow rates of 9 sccm and 18 sccm, respectively, and apertureoffsets according to an embodiment disclosed herein.

FIG. 18 shows a contour plot of organic vapor flux from a splitdepositor to the substrate according to an embodiment disclosed hereinin which the depositor apertures are overlaid, as is the contour of thestagnation plane separating various regions of process gas flow.

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed. Light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from theirsinglet states (“fluorescence”) as disclosed, for example, in U.S. Pat.No. 4,769,292, which is incorporated by reference in its entirety.Fluorescent emission generally occurs in a time frame of less than 10nanoseconds.

More recently, OLEDs having emissive materials that emit light fromtriplet states (“phosphorescence”) have been demonstrated. Baldo et al.,“Highly Efficient Phosphorescent Emission from OrganicElectroluminescent Devices,” Nature, vol. 395, 151-154, 1998;(“Baldo-I”) and Baldo et al., “Very high-efficiency green organiclight-emitting devices based on electrophosphorescence,” Appl. Phys.Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), which are incorporatedby reference in their entireties. Phosphorescence is described in moredetail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporatedby reference.

FIG. 1 shows an organic light emitting device 100. The figures are notnecessarily drawn to scale. Device 100 may include a substrate 110, ananode 115, a hole injection layer 120, a hole transport layer 125, anelectron blocking layer 130, an emissive layer 135, a hole blockinglayer 140, an electron transport layer 145, an electron injection layer150, a protective layer 155, a cathode 160, and a barrier layer 170.Cathode 160 is a compound cathode having a first conductive layer 162and a second conductive layer 164. Device 100 may be fabricated bydepositing the layers described, in order. The properties and functionsof these various layers, as well as example materials, are described inmore detail in U.S. Pat. No. 7,279,704 at cols. 6-10, which areincorporated by reference.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F4-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of emissive and host materials aredisclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which isincorporated by reference in its entirety. An example of an n-dopedelectron transport layer is BPhen doped with Li at a molar ratio of 1:1,as disclosed in U.S. Patent Application Publication No. 2003/0230980,which is incorporated by reference in its entirety. U.S. Pat. Nos.5,703,436 and 5,707,745, which are incorporated by reference in theirentireties, disclose examples of cathodes including compound cathodeshaving a thin layer of metal such as Mg:Ag with an overlyingtransparent, electrically-conductive, sputter-deposited ITO layer. Thetheory and use of blocking layers is described in more detail in U.S.Pat. No. 6,097,147 and U.S. Patent Application Publication No.2003/0230980, which are incorporated by reference in their entireties.Examples of injection layers are provided in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety. A description of protective layers may be found in U.S. PatentApplication Publication No. 2004/0174116, which is incorporated byreference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210,a cathode 215, an emissive layer 220, a hole transport layer 225, and ananode 230. Device 200 may be fabricated by depositing the layersdescribed, in order. Because the most common OLED configuration has acathode disposed over the anode, and device 200 has cathode 215 disposedunder anode 230, device 200 may be referred to as an “inverted” OLED.Materials similar to those described with respect to device 100 may beused in the corresponding layers of device 200. FIG. 2 provides oneexample of how some layers may be omitted from the structure of device100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided byway of non-limiting example, and it is understood that embodiments ofthe invention may be used in connection with a wide variety of otherstructures. The specific materials and structures described areexemplary in nature, and other materials and structures may be used.Functional OLEDs may be achieved by combining the various layersdescribed in different ways, or layers may be omitted entirely, based ondesign, performance, and cost factors. Other layers not specificallydescribed may also be included. Materials other than those specificallydescribed may be used. Although many of the examples provided hereindescribe various layers as comprising a single material, it isunderstood that combinations of materials, such as a mixture of host anddopant, or more generally a mixture, may be used. Also, the layers mayhave various sublayers. The names given to the various layers herein arenot intended to be strictly limiting. For example, in device 200, holetransport layer 225 transports holes and injects holes into emissivelayer 220, and may be described as a hole transport layer or a holeinjection layer. In one embodiment, an OLED may be described as havingan “organic layer” disposed between a cathode and an anode. This organiclayer may comprise a single layer, or may further comprise multiplelayers of different organic materials as described, for example, withrespect to FIGS. 1 and 2.

Structures and materials not specifically described may also be used,such as OLEDs comprised of polymeric materials (PLEDs) such as disclosedin U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated byreference in its entirety. By way of further example, OLEDs having asingle organic layer may be used. OLEDs may be stacked, for example asdescribed in U.S. Pat. No. 5,707,745 to Forrest et al, which isincorporated by reference in its entirety. The OLED structure maydeviate from the simple layered structure illustrated in FIGS. 1 and 2.For example, the substrate may include an angled reflective surface toimprove out-coupling, such as a mesa structure as described in U.S. Pat.No. 6,091,195 to Forrest et al., and/or a pit structure as described inU.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated byreference in their entireties.

Unless otherwise specified, any of the layers of the various embodimentsmay be deposited by any suitable method. For the organic layers,preferred methods include thermal evaporation, ink-jet, such asdescribed in U.S. Pat. Nos. 6,013,982 and 6,087,196, which areincorporated by reference in their entireties, organic vapor phasedeposition (OVPD), such as described in U.S. Pat. No. 6,337,102 toForrest et al., which is incorporated by reference in its entirety, anddeposition by organic vapor jet printing (OVJP), such as described inU.S. Pat. No. 7,431,968, which is incorporated by reference in itsentirety. Other suitable deposition methods include spin coating andother solution based processes. Solution based processes are preferablycarried out in nitrogen or an inert atmosphere. For the other layers,preferred methods include thermal evaporation. Preferred patterningmethods include deposition through a mask, cold welding such asdescribed in U.S. Pat. Nos. 6,294,398 and 6,468,819, which areincorporated by reference in their entireties, and patterning associatedwith some of the deposition methods such as ink-jet and OVJP. Othermethods may also be used. The materials to be deposited may be modifiedto make them compatible with a particular deposition method. Forexample, substituents such as alkyl and aryl groups, branched orunbranched, and preferably containing at least 3 carbons, may be used insmall molecules to enhance their ability to undergo solution processing.Substituents having 20 carbons or more may be used, and 3-20 carbons isa preferred range. Materials with asymmetric structures may have bettersolution processibility than those having symmetric structures, becauseasymmetric materials may have a lower tendency to recrystallize.Dendrimer substituents may be used to enhance the ability of smallmolecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the presentinvention may further optionally comprise a barrier layer. One purposeof the barrier layer is to protect the electrodes and organic layersfrom damaging exposure to harmful species in the environment includingmoisture, vapor and/or gases, etc. The barrier layer may be depositedover, under or next to a substrate, an electrode, or over any otherparts of a device including an edge. The barrier layer may comprise asingle layer, or multiple layers. The barrier layer may be formed byvarious known chemical vapor deposition techniques and may includecompositions having a single phase as well as compositions havingmultiple phases. Any suitable material or combination of materials maybe used for the barrier layer. The barrier layer may incorporate aninorganic or an organic compound or both. The preferred barrier layercomprises a mixture of a polymeric material and a non-polymeric materialas described in U.S. Pat. No. 7,968,146, PCT Pat. Application Nos.PCT/US2007/023098 and PCT/US2009/042829, which are herein incorporatedby reference in their entireties. To be considered a “mixture”, theaforesaid polymeric and non-polymeric materials comprising the barrierlayer should be deposited under the same reaction conditions and/or atthe same time. The weight ratio of polymeric to non-polymeric materialmay be in the range of 95:5 to 5:95. The polymeric material and thenon-polymeric material may be created from the same precursor material.In one example, the mixture of a polymeric material and a non-polymericmaterial consists essentially of polymeric silicon and inorganicsilicon.

Devices fabricated in accordance with embodiments of the invention canbe incorporated into a wide variety of electronic component modules (orunits) that can be incorporated into a variety of electronic products orintermediate components. Examples of such electronic products orintermediate components include display screens, lighting devices suchas discrete light source devices or lighting panels, etc. that can beutilized by the end-user product manufacturers. Such electroniccomponent modules can optionally include the driving electronics and/orpower source(s). Devices fabricated in accordance with embodiments ofthe invention can be incorporated into a wide variety of consumerproducts that have one or more of the electronic component modules (orunits) incorporated therein. Such consumer products would include anykind of products that include one or more light source(s) and/or one ormore of some type of visual displays. Some examples of such consumerproducts include flat panel displays, computer monitors, medicalmonitors, televisions, billboards, lights for interior or exteriorillumination and/or signaling, heads-up displays, fully or partiallytransparent displays, flexible displays, laser printers, telephones,cell phones, tablets, phablets, personal digital assistants (PDAs),laptop computers, digital cameras, camcorders, viewfinders,micro-displays, virtual reality displays, augmented reality displays,3-D displays, vehicles, a large area wall, theater or stadium screen, ora sign. Various control mechanisms may be used to control devicesfabricated in accordance with the present invention, including passivematrix and active matrix. Many of the devices are intended for use in atemperature range comfortable to humans, such as 18 C to 30 C, and morepreferably at room temperature (20-25 C), but could be used outside thistemperature range, for example, from −40 C to +80 C.

As previously described, OVJP printing techniques typically use a vaporflow of a bulk carrier gas with evaporated molecules, which is sprayedon a substrate through a nozzle. The molecules sublimate on thesubstrate when the gas mixture hits the surface. Material typically isdeposited from a round or rectangular nozzle with a width (x-direction)and length (y-direction). A line is sprayed by moving the nozzlerelative to the substrate in the y-direction. The Gaussian thicknessprofile of a thin film features printed by OVJP may not be ideal forOLED printing applications because OLEDs typically require uniformthickness over their active area. Thickness uniformity is currentlyobtained by printing features in multiple offset passes. This disclosuredescribes a depositor with a split delivery aperture that provides amore desirable deposition profile and allows for printing features withmore uniform thickness. This depositor geometry is expected to reduceTAKT time because it allows an OLED array to be printed in fewer passes.It is furthermore expected to reduce contaminant exposure and improvethe operational lifetime of printed OLEDs since it minimizes the periodbetween the initiation and completion of EML deposition for each OLED inan array. This depositor geometry can be readily made using techniquesalready used to fabricate DEC (delivery-exhaust-confinement) OVJPmicronozzle arrays, such as those described in U.S. Pat. No. 9,583,707,the disclosure of which is incorporated by reference in its entirety.

For example, in many applications it may be preferred to createdeposition profiles that are trapezoidal in shape, such as with auniform top side and steep skewed chamfers as shown in FIG. 3. However,techniques to do so using conventional OVJP arrangements are limited.The deposition profile that results from use of a particular nozzle canbe described by the statistical distribution type and parameters, wherethe kurtosis of the distribution describes the resulting shape. Thedeposition profile in x-direction from a round or rectangular nozzleshape generally will have a typical Gaussian shaped distribution thatbroadens with an increasing distance from nozzle to substrate. Examplesof such deposition profiles and associated distribution types are shownin FIG. 4. A high kurtosis or leptokurtic distribution gives strongskewness of the sides and a high peak in the center. A negative kurtosisgives low skewness and can result in a platykurtic profile that shows aplateau in the center.

To deposit a pattern that approaches a trapezoid shape with 90%uniformity over a certain width, it is possible to stitch individualGaussian patterns at the 50% or FWHM (Full Width Half Maximum) level.The total width is then the spray uniformity width and the sum of bothchamfers or tails. In some applications where OVJP is used to depositsub-pixel lines, such as fabrication of displays, it may be desirablefor the spray uniformity width to be at least the width of the sub-pixelactive area. Further, it generally is preferred or necessary for thetotal width of a deposited line to be less than the distance between thetwo neighboring sub-pixel lines to prevent different colors of emissivematerials from mixing during fabrication. In many cases the uniform partof the pattern in the central plateau is a primary deposition goal, withthe sides of the profile preferably being sufficiently constrained so asto avoid contamination of neighboring areas. Preferably, the sides ofthe final deposition are vertical or approximately vertical, or with aside angle as steep as possible.

FIG. 5 shows an example of such a pattern, having a central width withhigh uniformity. The total resulting deposition pattern 540 may beachieved by deposition of two or more shifted Gaussian profiles 510,520, 530, for example, resulting from two or more nozzle passes or twoor more sequential shifted nozzles. More generally, any number ofnozzles and/or passes of one or more nozzles may be used to fabricate orapproximate a desired deposition profile.

When the shift in x-direction of two neighboring deposition patternsfrom two nozzles having the same shift is less than the FWHM of thedeposition profile, the combined pattern will be a Gaussian profilewhich is wider and higher than the individual patterns. FIG. 6 shows anexample of such a profile 640 formed from three depositions 610, 620,630.

When the shift of two depositions is greater than the FWHM of theindividual deposition profile, the combined profile will result ineither a platycurtic profile or (with a larger shift) in a profile withtwo neighboring peeks. A shift that is only slightly larger thanapproximately the FWHM results in a deposition profile with a middlesection having have a width that satisfies the 90% uniformity demand.The width of this plateau is wider than the narrow plateau in a singleprofile by the amount of the shift. Adding more profiles, such as bymaking additional passes with one or more nozzles, each shifted withrespect to the neighboring profile in the same fashion, will similarlywiden the area with 90% uniformity.

To meet the conventional desired trapezoid shape, the width of the baseshould not be so wide that it covers the neighboring sub pixel activeareas. However, the base width increases proportional to the added widthfrom the shifted patterns. One approach to limit the base width whileachieving a desired width with 90% uniformity is to add more depositionswith higher kurtosis profiles, i.e. adding more profiles that arenarrower. This can result in a combined profile with the same area of90% uniformity, but with steeper side walls to the profile, resulting ina narrower base of the combined profile. Such techniques require acombination of more and narrower profiles, and have several drawbacks.For example, narrower profiles require a shorter distance between thenozzle and the substrate and/or narrower nozzles to achieve the desiredprofile shape. As another example, combining narrower profiles requiremore accurate positioning of one profile with respect to another,requiring greater precision in control of the deposition apparatus. Moregenerally, combining more patterns from a single nozzle requiresincreased processing time, whereas generating a combined profile frommore nozzles increases the number of nozzles in operation at any onetime and thus the complexity and cost of the deposition system.

Accordingly, a preferred solution to achieve desired deposition profilesis a single nozzle arrangement that deposits all the components of thedesired composite profile in a single pass, without the need formultiple narrow nozzle apertures. Embodiments of such an arrangement areprovided herein, which include a series of deposition nozzle shapes thatgenerate a cumulative deposition profile of a substantial trapezoidshape as they move in the y-direction.

FIG. 7 shows example nozzle aperture arrangements according toembodiments disclosed herein. The shapes are shown as viewed from aboveor below the deposition apparatus, e.g., viewed from the substrate in adirection away from the surface on which material is to be deposited,toward the deposition apparatus. The shapes of the single nozzleaperture in these embodiments have areas that contribute to the overalldeposition pattern from the nozzle in essentially discrete sections. Ineach example, a central area I results in a central profile I indicatedin the deposition graph below. Similarly, the other nozzle apertureareas II and III result in smaller deposition profiles shifted from thecenter profile I as shown in the corresponding deposition profiles shownbelow. As previously described, in each example the y-axis indicates therelative direction of movement of the substrate on which material isdeposited and the deposition system.

The nozzle shapes are designed in such a way that each central section Iprovides a wide Gaussian shape with low kurtosis. That is, if the nozzleaperture included only the central section I, the resulting depositionprofile would be Gaussian with low kurtosis. At the outer sides, thedeposition profiles result from relatively narrower nozzle sections todeposit a profile portion with higher kurtosis. As discussed above, thesuperposition of these contributions may provide a shape that is orapproaches a trapezoid. Specifically, the resulting shape may include arelatively flat mesa region in the middle, and relatively sharp verticalwalls on either side.

Other variations on the nozzle aperture shapes shown in FIG. 7 may beused. For example, FIGS. 8A-8C show variations on the third arrangementshown in FIG. 7. In some arrangements, such as FIGS. 8A and 8B, thedeposition nozzle may include a single continuous aperture withdifferent regions. In other arrangements, the deposition nozzle mayinclude multiple distinct regions such as shown in FIG. 8C. Regardlessof whether one or several apertures are present, each of the areas 1, 2and 3 may all contribute to the combined deposition profile aspreviously disclosed.

In some embodiments, exhaust channels or apertures may be provided oneither side of the deposition nozzle. For example, the arrangementsshown in FIGS. 8A-8C include exhaust channels 810 arranged on eitherside (along the x-axis) of the deposition aperture. In the examplesshown the exhaust channels are provided as a single rectangular apertureon either side of the combined deposition apertures, though moregenerally any arrangement of one or multiple exhaust channels may beused. Each exhaust channel may be in fluid communication with alow-pressure region, vacuum source, or the like, so as to removeundeposited material from the region or regions between the substrateand the deposition apparatus. The exhaust channels also may provideregions of different pressure or active confinement flows on either sideof the deposition nozzle to further confine and/or shape the resultingdeposition profile as disclosed herein. Various arrangements andexamples of exhaust and confinement channels are described in U.S.application Ser. No. 14/643,887, filed Mar. 10, 2015, 14/730,768, filedJun. 4, 2015, and 15/290,101, filed Oct. 11, 2016, the disclosure ofeach of which is incorporated by reference in its entirety. Generally,as disclosed in those applications, micronozzle array technology whichutilizes a combination of deposition apertures surrounded by exhaustapertures and a gas confinement flow to confine the line width andoverspray uses the concepts of Deposition, Exhaust, and Confinement, andaccordingly may be referred to as a DEC process or device. FIG. 9 showsthe separate feature profiles printed by the top and bottom depositorsof FIG. 8C that sum to form the desired profile. FIG. 9 shows the leftskewed deposition profile generated by section 1 and FIG. 10 shows theright skewed profile generated by section 3.

FIGS. 11A, 11B, and 11C shows the organic vapor flux generated on thesubstrate by the aperture sets depicted FIGS. 8A, 8B, and 8C,respectively. Each line indicates the flux profile generated at a givencross section in y, as a function of x. Deposition on substrate sectionsunder sections 1 1101 and 3 1102 is skewed to one side, as shown in FIG.9. Section 2 generates a region of high flux 1103 that is symmetric inthe x dimension. This type of feature is generated by the configurationsof FIGS. 8A and B, but not of FIG. 8C. The cross sections of organicflux are summed to generate the deposition profiles plotted in FIG. 12.Integrated flux is plotted on the vertical axis as a function of x.FIGS. 12A and B, which correspond to aperture configurations in FIG. 8Aand 8B, respectively, have maxima in the center due to the opendeposition aperture at the center of each configuration. The maxima ofFIG. 12C symmetric and off-center, generating a more mesa-likedeposition profile, with a wider top and less kurtosis. The nozzledesign depicted in FIG. 8C is therefore a preferred embodiment in thiscase.

The use of gas confinement is a departure from conventional OVJPconcepts since it uses a chamber pressure of 50 to 300 Ton, rather thanhigh vacuum. Overspray is reduced or eliminated by using a flow ofconfinement gas to prevent the diffusive transport of organic materialaway from the desired deposition region. A schematic depositor design isshown from the perspective of the substrate in FIG. 13. Such anarrangement uses rectangular delivery 1301 and exhaust apertures 1302similar to those previously shown and described with respect to FIG. 8,which can be easily manufactured. The flow through the delivery aperturecontains organic vapor entrained in an inert delivery gas. The exhaustapertures withdraw gas from the region under the depositor at a massflow rate exceeding the delivery flow. They remove the delivery flow andany surplus organic vapor entrained within it, as well as a balance ofconfinement gas drawn from the ambient surrounding the depositor.Depositors of the DEC design are generally are arranged so that the longaxes of their apertures are parallel to the direction of printing 1303,i.e., the y-axis as previously described. Depositors 1304 are usuallyarranged linearly on a micronozzle array 1305, so that each depositorborders another on at least one its side boundaries 1306. The top andbottom edges of the depositor 1307 may be defined by the edges of alinear micronozzle array that includes multiple micronozzle arrangementsas shown. Distribution channels 1308 placed between depositors mayprovide a source of confinement gas along the sides of each depositor.Confinement gas flows inward from the edges of the micronozzle array ifthese channels are omitted. Arrays are typically designed to minimizecrosstalk between depositors so printed features are uniform across thewidth of the array. Additional exhaust apertures can be placed at theends of the array, for example, to minimize edge effects. The flow fieldunder such a micronozzle array therefore has periodic symmetry.

The average thickness t of a printed film is given by t=jπ/ρ, where j isthe mass flux of organic vapor onto the substrate, τ is the period oftime a given point on the substrate is under the aperture, and ρ is thedensity of the condensed organic material. Because τ=l/v, where l is thelength of the aperture and v is the relative velocity of the substrate,a longer delivery aperture permits a given point on the substratesurface to remain under the aperture for a longer time at a given printspeed. This permits faster printing, so longer apertures may bepreferable in many applications. For example, embodiments disclosedherein may allow for fabrication of an emissive layer, such as for anOLED, in not more than 1.0 s, 0.1 s, or 0.01 s. However, deliveryaperture dimensions may be subject to limitations of the fabricationprocess used to create the deposition device. For example, they can beabout 20-30 times longer than they are wide if fabricated using deepreactive ion etching. Smaller nozzles print higher resolution features,but fabrication and operational concerns usually set the practicalminimum size. As a specific example, optimal delivery apertures forprinting 120 μm wide features generally will have a width of 15-20 μm.Other dimensions may be used depending upon the feature size desired.

FIG. 14 shows the arrangement of deposition and exhaust channels and thestreamlines of the delivery 1401 and confinement flows 1402 in crosssection normal to the direction of printing. The delivery flow passesfrom a delivery channel 1403, through a delivery aperture 1301, underthe delivery-exhaust (DE) spacer 1404, through an exhaust aperture 1402,and finally out of the deposition zone through the exhaust channel 1405.Confinement gas flow comes from a far-field source 1406 and travelsbeneath the surface of the depositor before exiting through the exhaustaperture. The delivery flow is confined to the region between theexhaust channels by the confinement gas flowing into the exhaustaperture along the surface of the substrate. The surface where the twoflows meet is defined as the stagnation surface 1407, where velocity inthe x direction, orthogonal to both the substrate normal and thedirection of line printing, v_(x)=0. The width of the region enclosed bythe stagnation surface corresponds well to the width of printedfeatures, so the position of the stagnation plane controls the shape ofthe deposition zone 1408.

FIGS. 15A and 15B show the cross-sectional profiles of the thicknessesof a thin film feature printed by a depositor with a single deliveryaperture in one or two passes, respectively, according to an embodimentdisclosed herein. The cross sectional thickness profile 1501 of afeature printed by an individual DEC depositor is approximatelyGaussian, as shown in FIG. 15A. The vertical axis 1502 is film thicknessin arbitrary units and the horizontal axis 1503 is displacement from thedelivery aperture centerline in the x direction in microns. There aretwo basic criteria of interest for the shape of deposited feature—widthand thickness uniformity. The width includes both the gross feature andany overspray surrounding it, since overspray can contaminate adjacentfeatures and limit resolution. Full width to 5% of maximum (FWSM) is thewidth 1504 at between two points on the opposite sides of a featurecross section that are at 5% of the maximum feature thickness 1505. Thetotal tolerable width for a printed feature is typically about 160 μmfor an average high resolution display application, including regionscontaminated by overspray. The uniformity refers to the differencebetween the maximum and minimum 1506 thickness of over a width 1507,typically 50 μm, across the center of the feature, divided by theaverage thickness over that width. This width corresponds to anelectrode on a typical subpixel of an OLED display. It is generallyrequired for printed OLEDs to have a uniform or nearly uniform thicknessover their active width to operate properly.

As disclosed herein, adequate uniformity can be achieved by printingeach feature in two passes, 1508 and 1509, with an offset of somewhatless than the pixel width between the print passes 1510. Two offsetfeatures superimpose to create a composite feature 1511 having a moremesa-like profile. As a specific example, when an offset of 40 μm isdesirable for printing uniformity (such as may be common forhigh-resolution, full-color displays), the width of line printed by eachpass should be no more than 120 μm. However, double printing increasesTAKT time compared with single-pass printing and thus may be desirableto avoid in many applications.

Furthermore, printing in multiple passes creates an interval duringwhich the emissive layer (EML) of an OLED is partially printed and,therefore, more vulnerable to environmental contamination than acompleted feature. For example, it has been shown in H. Yamamoto, C.Adachi, M.S. Weaver, and J. J. Brown Appl. Phys. Lett. 100, 183306(2012) that the operational lifetime of a phosphorescent OLED issignificantly reduced if it is exposed to traces of water vapor betweenthe initiation and completion of EML growth. It is much less sensitiveto contamination once the EML is completed. The time between start andcompletion of a 300 Å thick EML is on the order of 0.1 s or less for asubpixel printed by OVJP. If only a single printing pass is required,this greatly reduces the interval in which the EML may becomecontaminated. In contrast, vacuum thermal evaporation (VTE) typicallyrequires one or more minutes to deposit an EML, suggesting that a singleprint pass OVJP may be capable of depositing even higher purity filmsthan VTE.

According to embodiments disclosed herein, the effect of two-passprinting can be achieved in a single pass using depositor with adelivery aperture split into two sections that are offset byapproximately the distance between two print passes by a depositor witha single delivery aperture. FIG. 16A shows the split nozzle design andFIG. 16B shows a resulting deposition profile. The delivery aperture issplit into upper 1601 and lower apertures 1602 along its midline 1603.The exhaust apertures, however, may remain straight and continuous. Theupper and lower delivery apertures may be discontinuous and the centerof each aperture is separated by an offset distance 1604 that can beoptimized for a desired feature size and uniformity. A 40 μm offsetworks well for display printing applications. The DE spacers 1605 oneach side of an aperture are asymmetric, differing in width by theoffset. The forward and rear components of the depositor act almostindependently, so the change in the thickness profile of the printedfeature is a largely geometric effect.

In such a configuration, the exhaust aperture withdraws organic vapormore aggressively on the side of the narrower DE spacer. This results ina sharp sidewall 1608 that defines the outer edge of the aggregatefeature. The material deposited on the side of the wider DE spacer 1609does not define as steep an edge, since its thickness tapers moregradually. Less organic vapor is removed by the exhaust on the side ofthe wide spacer, so material utilization efficiency improves withgreater offset width. Feature profiles become both wider and moreasymmetric with greater offset.

Furthermore, a single deposition aperture located off-center between twoexhaust channels or two regions of exhaust channels generally willresult in an asymmetric deposition profile. For example, FIGS. 9 and 10show example deposition profiles resulting from aperture sections 1 and3, respectively, in the example arrangement shown in FIG. 8C. Theseskewed profiles have relatively steep sidewalls on one side of theresulting deposition profile. The difference in skewness (shown aspositive and negative in FIGS. 9 and 10) of such asymmetric depositionprofiles may be combined by using a deposition nozzle as shown in FIG.8C to provide a trapezium deposition profile with limited base width.Specifically, the combination of skewed profiles as shown may result ina platykurtic profile having desirable dimensions, provided the distancebetween the profiles is chosen correctly. Accordingly, in someembodiments the arrangement of deposition nozzle as shown in FIG. 8Cprovides a preferred geometry to deposit the strongest difference inskew for an asymmetric profile.

As previously noted, the example nozzle arrangements in FIGS. 8A-8B mayinclude a deposition aperture section 2 that is omitted from anarrangement as shown in FIG. 8C. This aperture section generally willdeposit a Gaussian profile in the middle of the combined profile, with awider, more symmetric deposition pattern. Such a deposition profile maybe used to fill a dip between the two skewed asymmetrical profiles thatresult from deposition through aperture areas 1 and 3.

In some embodiments, the deposition aperture areas 1 and 3 in anarrangement as shown in FIGS. 8C and 16A may nearly touch in the Ydirection. That is, the two areas may be arranged that there is arelatively short or zero distance between the closest points of the twoareas, such that they are or operate as two separate apertures withinthe deposition device. Due to the proximity of the aperture areas, thereis an area between where deposition flows out of the aperture areasinteract. This interaction, which may be referred to as “short-cutting,”may cause an increased deposition in the central region of the nozzlearrangement, resembling the effect of an actual deposition aperture 2disposed between apertures 1 and 3. In effect, the removal of depositionflow towards the most outer-located exhaust may be partially or entirelyblocked by the other deposition aperture area. This may create a localarea with increased efficiency, and thus a higher local depositionprofile. Simulations also indicate that for some nozzle dimensions, theabsence of a physical aperture 2 may still result in an additional“filling” effect in between the two dips in the profiles resulting fromthe two deposition apertures 1 and 3 as previously disclosed.

As the dimensions of aperture areas 1 and 3 are increased along they-axis, i.e., along the printing direction, the effect of this fill-inmay be less pronounced. After a certain length, the addition of aphysical deposition aperture area 2 may be desirable or required to fillin the resulting dip in between the profiles from the areas 1 and 3.

FIGS. 11-12 show simulation results for the nozzle and exhaust channelarrangements illustrated in FIG. 8A-8C, respectively. FIGS. 11A-11C,respectively, show the partial contributions in the x-direction atdifferent y-sections. FIGS. 12A-12C show, respectively, the weighted sumof the profiles, i.e., the expected deposition profiles (with substratesurface at the top). Notably, the results indicate that the arrangementshown in FIG. 8C also delivers a small symmetric Gaussian distributionin the center due to the crosstalk at the intersection plane of the twoseparate nozzle sections.

FIG. 16B shows deposition profiles generated by the upper half of thedepositor arrangement shown in FIG. 16A. Only organic materialoriginating from the top delivery aperture appears in this distribution.Material from the lower delivery aperture is omitted. The distributionis analogous to the profile plotted in FIG. 10. The center of the topdelivery aperture is offset 1604 from that the bottom delivery apertureby 20, 30, 40, and 50 μm for 9 sccm (1606) and 18 sccm (1607) exhaustflows. This is consistent with the simulation results shown in FIGS.11-12. The asymmetry of the delivery aperture placement between theexhaust apertures generates a deposition profile that is lopsidedrelative to that of a symmetric depositor. Maximum deposition is skewedtowards the side where the delivery and exhaust apertures are close, andthe deposition profile has a longer tail on the side further from theexhaust.

The thickness profile of the feature generated by the whole depositordepicted in FIG. 16A is shown in FIG. 17A (9 sccm exhaust flow) and 17B(18 sccm exhaust flow). Deposition from the top delivery aperture shownin FIG. 16B is summed to an analogous distribution generated by thebottom delivery aperture for a variety of offsets. The thicknessprofiles generated by split depositors with 20 μm (1701), 30 μm (1702),40 μm (1703), and 50 μm (1704) offsets feature flatter tops than asingle aperture depositor (1705), while showing a similar degree ofsidewall sharpness. The FWSM, uniformity, and deposition rate for thesedesigns are shown in Table I. Printing resolution generally improveswith increased exhaust flow, but this is at the expense of decreaseddeposition rate since more of the organic vapor leaves through theexhausts. Deposition rate improves with offset width due to theincreased material utilization efficiency from long DE spacer. Widthincreases linearly with offset, as expected. Uniformity also increasessince the tops of the profiles become flatter with greater offsetbetween their component maxima. Lower exhaust flows also improveuniformity, although this is at the expense of increased width. Theseeffects are summarized in Table I.

TABLE I Offset FW5M (μm) Uniformity (%) Dep. Rate (Arb.) (μm)\Exhaust 9sccm 18 sccm 9 sccm 18 sccm 9 sccm 18 sccm  0 112 87.4 71.0 29.2 28,50010,900 20 134 108 82.4 66.2 34,800 15,100 30 145 118 90.0 80.8 37,30016,400 40 154 129 96.5 90.8 42,000 17,900 50 166 140 97.5 96.8 43,50019,800

FIG. 18 shows a cross section of a stagnation surface 1801, i.e., aregion where the velocity of gas in the x direction is zero and thedirection of flow reverses, in the plane of the substrate for the caseof 9 sccm exhaust, 50 μm offset, and side fed confinement 1802. Thelighter closed contours represent the intensity of organic vapordeposition on the substrate, with the innermost contours 1803 receivingthe most material. Deposition becomes negligible beyond the outermostcontour 1804. The regions covered by the delivery and exhaust aperturesare shaded and the axes are ruled in microns. The width of thedeposition region corresponds well to the width of the outer stagnationsurface contour 1805.

Flow between the stagnation surface and the inner edge of the exhaustaperture comes from the delivery aperture. Notably, the stagnationsurface tends towards the outer edge of the exhaust aperture 1806 whenit is adjacent to the narrow delivery-exhaust DE spacer, and tendstowards the inner edge of the aperture 1807 when it is adjacent to thewide DE spacer. This is because the closer exhaust aperture draws agreater fraction of the flow from each delivery aperture. The middlesection of the stagnation surface runs underneath both deliveryapertures. While the outer sections represent the edge of the depositionzone, the inner section crosses through the regions of fastestdeposition under each component of the split delivery aperture. Thestagnation plane passes through the center of the delivery flow, whereflow is directed vertically downward. Confinement gas should be fed fromthe sides, as opposed to the ends, of the depositor to ensure the mosteven possible confinement flow into the exhausts. Well confined anduniform organic vapor deposition thus may be achieved if the outerregions of the stagnation surface remain parallel to the exhaustapertures along the full length of the depositor.

Micronozzle arrays containing split aperture depositors can be readilyfabricated by a variety of techniques. For example, arrays as disclosedherein may be fabricated by bonding SI wafer pairs with arrays oftrenches on their surfaces formed by deep reactive ion etching. Bondingthe wafer pair creates closed channels. A wafer pair is diced to formindividual micronozzle arrays with depositors along their edges. Theapertures of the depositors are defined by the intersection of a channeland a dicing line. Such a process is described in greater detail in U.S.application Ser. No. 14/464,3887, filed Mar. 10, 2015 (U.S. Pub. No.2015/0376787). Continuous apertures that are symmetric about the bondline, such as the exhaust apertures, are formed from mirror imagetrenches that overlay each other at dicing line. Conversely, aperturesthat are only present on one side of the bond line are created fromtrenches that do not overlay each other. Each aperture of the splitdelivery aperture pair is defined along the bond line by an unetchedwafer surface and around the rest of its perimeter by an etched trenchin the etched surface of the opposite wafer. The trench centerlines areseparated from each other by the desired aperture offset distance.

In an embodiment, an optimized split depositor has two 15×200 μmapertures. The apertures are arranged end to end with centerlinesseparated by an offset of 40 μm, in the same basic arrangement as shownin FIG. 16A. The delivery apertures are surrounded by a pair of 30×500μm exhaust apertures. The spacers between the exhaust and deliveryapertures are 15 μm on the narrow side and 55 μm on the wide side.Confinement gas is fed from the sides of the depositor throughdistribution channels between depositors arranged in a linear array.

As disclosed above, embodiments disclosed herein may decrease processtime since desired deposition profiles may require only a single passper line of material to be deposited, allowing for greater distances tobe covered per nozzle in the same time than would be achievable usingconventional techniques. Furthermore, the accuracy required for nozzlepositioning according to embodiments disclosed herein does not requireas accurate repeatability as conventional techniques, in which two ormore passes are used and accordingly a relatively high overlay accuracyis needed. Embodiments disclosed herein also may provide for moreefficient material use. Because larger distance between a depositionchannel and an exhaust channel arranged on one side of the nozzle may beused, the overall deposition efficiency of the nozzle (i.e. the amountof organic material present in the deposition flow exiting the nozzlethat ultimately is deposited on the substrate) will be higher than inconventional arrangements, because the material has more chance tointeract with the substrate and before it is removed via the exhaust.Furthermore, the disclosed method reduces the interval between theinitiation and completion of emissive layer deposition for each sectionof substrate, since a uniform deposition can be performed in fewerpasses. This may improve device lifetime.

Experimental

Depositors were simulated by computational fluid dynamics (CFD) inCOMSOL MultiPhysics 5.2. A laminar flow of 6 sccm of helium was fed intothe delivery aperture or aperture cluster. The exhaust boundarycondition was also specified as a laminar flow rate. The micronozzlearray was heated to 250° C. and the substrate was at 20° C. Themicronozzle array surface and substrate were separated by a fly heightof 50 μm and a millimeter square region surrounding the depositor wassimulated. The pressure of the helium or argon ambient surrounding thesimulated volume was 200 Torr. Gas mixing was simulated using COMSOL'sTransport of Concentrated Species model for delivery and confinementgasses of different species. Transport of organic vapor through thesimulated region was solved with the steady state convection-diffusionequation. Diffusivity of the gas mixture was calculated from kinetictheory of gasses and the model of Fairbanks and Wilke (1950). Thesimulated geometry was that of the preferred embodiment described inparagraph 81, except the width of the larger DE spacer was changedbetween cases to vary the offset between the top and bottom deliveryapertures of the depositor.

It is understood that the various embodiments described herein are byway of example only, and are not intended to limit the scope of theinvention. For example, many of the materials and structures describedherein may be substituted with other materials and structures withoutdeviating from the spirit of the invention. The present invention asclaimed may therefore include variations from the particular examplesand preferred embodiments described herein, as will be apparent to oneof skill in the art. It is understood that various theories as to whythe invention works are not intended to be limiting.

We claim:
 1. A method of fabricating a deposition device, the methodcomprising: dicing a wafer pair to form micronozzle array channelscomprising a plurality of deposition apertures along the edges of eachwafer, each aperture being defined by the intersection of a channel anda dicing line; and bonding the wafer pair to form a deposition nozzlecomprising: a first exhaust aperture; a second exhaust aperture; a firstdeposition aperture disposed between the first exhaust aperture and thesecond exhaust aperture and closer to the first exhaust aperture thanthe second aperture; and a second deposition aperture disposed betweenthe first exhaust aperture and the second exhaust aperture and closer tothe second exhaust aperture than the first exhaust aperture, wherein thesecond deposition aperture is offset from the first deposition aperturealong an axis of the nozzle.
 2. The method of claim 1, wherein,subsequent to bonding the wafer pair to form a deposition nozzle, forany line drawn between and perpendicular to the first exhaust apertureand the second exhaust aperture, the line crosses no more than one ofthe first deposition aperture and the second deposition aperture.
 3. Themethod of claim 1, wherein, subsequent to bonding the wafer pair to forma deposition nozzle, the second deposition aperture is offset from thefirst deposition aperture along an axis of the nozzle.
 4. The method ofclaim 1, wherein, subsequent to bonding the wafer pair to form adeposition nozzle, there are no more than two deposition aperturesdisposed between the first exhaust aperture and the second exhaustaperture.
 5. The method of claim 1, wherein, subsequent to bonding thewafer pair to form a deposition nozzle, the first deposition apertureand the second deposition aperture have the same dimensions.
 6. Themethod of claim 5, wherein each of the first deposition aperture and thesecond deposition aperture are rectangular.
 7. The method of claim 1,wherein, subsequent to bonding the wafer pair to form a depositionnozzle, the first exhaust aperture and the second exhaust aperture arecontinuous.
 8. The method of claim 1, further comprising fabricating thechannels using deep reactive ion etching.
 9. The method of claim 1,wherein dimensions of the micronzzle array channels are defined bythicknesses of channels etched into the wafer pair.
 10. The method ofclaim 1, wherein dimensions of the delivery apertures are defined byintersections of the channels within the wafer and a lower edge of thewafer formed by the step of dicing the wafer pair.
 11. A device fordeposition of a material onto a substrate, the device comprising: adeposition nozzle comprising: a first exhaust aperture having a longedge and a short edge that is shorter than the long edge; a secondexhaust aperture having a long edge and a short edge that is shorterthan the long axis edge; a first deposition aperture disposed betweenthe first exhaust aperture and the second exhaust aperture, at leastpartially crossing a line extending that extends between andperpendicular to the long edge of the first exhaust aperture and thelong edge of the second exhaust aperture without crossing any exhaustaperture, the first deposition aperture being disposed and closer to thefirst exhaust aperture than the second aperture; and a second depositionaperture disposed between the first exhaust aperture and the secondexhaust aperture and closer to the second exhaust aperture than thefirst exhaust aperture, wherein, for any line drawn between andperpendicular to the first exhaust aperture and the second exhaustaperture, the line crosses no more than one of the first depositionaperture and the second deposition aperture.
 12. A device comprising anOLED, wherein the OLED comprises: a first electrode disposed over asubstrate; a first emissive layer disposed over the first electrode; anda second electrode disposed over the emissive layer, wherein the firstemissive layer is fabricated using no more than one pass of a depositiondevice comprising a nozzle in fluid communication with a source ofmaterial to be deposited over the substrate in not more than 1.0 sbetween the initiation and conclusion of deposition on each point on theprinted surface of the substrate.